WebSQL is a SQL-like （1） language for extracting information from the web. Its capabilities for performing navigation of web （2） make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a （3）, all the pages that can be reached from a given URL through （4） that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common （5） Interface.

• A、query 
• B、transaction 
• C、communication 
• D、programming